Setup & Fixity

Wall Setup

The wall setup allows you to set up the masonry wall as a single leaf or cavity wall, introduce piers to stiffen the wall or as a masonry column.

As a single leaf or cavity wall, specify the wall width and effective width factor if other than 1, specify the wall height and effective height factor. Then modify the thicknesses of the inner and outer leafs as required.

If the wall is stiffened with piers, specify the outstand ratios OR1 and OR2. These are usually in the range of 4 to 6 times the wall leaf thickness and refer to the outstand to either side of the pier that will define the flange length of the stiffened part of the wall.

The distance D0 to the centre of the first pier can be set along with the pier centres CCP, both in millimetres. If D0 is left to zero then the piers will be centred on the wall. Finally specify the pier thickness and width.

Note that if the wall is a vertical cantilever, eg, a boundary or garden wall, the part of the wall length in between the stiffened portions of the wall may still only have the resistance of thinner portion of the wall and so be the weakest point that is governing the design. Piers centres could be brought closer in this instance to increase the overall wall resistance.

Masonry columns can also be set up. You can specify the breadth and thickness of the column on plan, along with the column height and effective height factors in both axes.

Edge Fixity

The edge fixity option allows you to define the edge fixities around all 4 sides of the wall independently.

You can have both the inner and outer leafs having the same fixities or switch off the 'Outer leaf has the same value as inner' option and define the edge fixities for the outer leaf to be different than those of the inner leaf. This is particularly useful where the inner leaf is 'pinned' to a concrete frame and the outer leaf is continuous outside the concrete frame. In these sort of cases a weighted percentage fixity is applied to the wall edge in question.

The percentages represent:-  a free leaf is -100%, a pinned leaf is 0% and a rotationally fixed leaf is +100%.

The above inner and outer leaf fixities would give the overall edge fixities shown on the wall below.

For the top of the wall (inner pinned and outer free) the degree of fixity is (0 - 100)/2 = -50%.

For the side edges of the wall (inner pinned and outer fully fixed) the degree of fixity is (0 + 100)/2 = +50%.

The base if fully fixed = +100%.

When the wall is analysed, these percentage fixities are taken into account.

You can also set the edge fixity as partially fixed as well if you think the degree of fixity is somewhere between pinned and fixed (+ve %) or pinned and free (-ve %).